1. Field of the Invention
The invention is directed to door closer check devices of the type having a reciprocable spring-biased door closing piston assembly combined with a latch plate that is transversely slidable along the length of the piston rod and can be set to prevent the door from closing completely. More specifically, the invention relates to an apparatus for setting the latch plate on such devices electronically, such that the door may be selectively positioned partially or completely open indefinitely and until subsequently released.
2. Prior Art
Doors such as with side-hinged screen doors, storm doors, and the like conventionally include means that close the door. Such means may be as simple and inexpensive as a spring that pulls a released, unblocked door closed in a generally uncontrolled fashion. More controlled means by which a released, unblocked door may be closed include a piston assembly. The door piston assembly typically consists of a cylindrical tube attached at one end to a bracket connector on the door. Within the inner surface of the cylindrical tube a spring-loaded piston may slide. A reciprocating connecting rod extends from the piston and out of the cylindrical tube. The end of the connecting rod opposite to the end carried within the cylindrical tube typically is attached to the door frame. When the door is opened, the connecting rod is pulled from the cylindrical tube, causing the piston to travel within the inner surface of the cylinder and thereby a spring coiled between an inner wall of the cylinder and the piston to compress. Upon the door being released, energy stored within the coiled spring pushes against a surface of the piston, causing it to slide within the cylinder and the connecting rod to be drawn back within the cylindrical tube and thereby the door to close. The retracting momentum of the piston is typically cushioned by compression of fluid such as oil or air inside the cylindrical tube to create a damping resistance contrary to the force that propels the door to close for better control of the speed and force at which the door closes.
Many conventional door closing devices include a latch plate that can be set to prevent the connecting rod from being drawn back within the cylindrical tube and thereby the door from being closed partially or completely. The latch plate typically has an aperture of a size and shaped so that the connecting rod may extend therethrough and so that the latch plate may easily slide transversely along the length of the rod. The latch plate may be rounded or L-shaped (as for example in U.S. Pat. Nos. 2,808,608 and 3,032,806) with an extending flange or embossment sized to approximate the outer diameter of the cylindrical tube. Latch plates conventionally are manually set once the door is opened on a position along the connecting rod. After the door is released, the connecting rod begins to be drawn back within the cylinder. However, with the latch plate manually set, the proximal end of the cylindrical tube makes first contact with one of the outer edges of the extending latch plate flange, causing the latch plate to tilt or rotate slightly. In consequence, the edge of the latch plate aperture makes contact with diametrically opposite sides of the connecting rod. As the cylindrical tube begins to push with greater force against the latch plate, the resistance between the edge of the latch plate aperture and the connecting rod increases thereby slowing, and eventually altogether preventing the further inward movement of the connecting rod. When the full closing force of the door closer is brought to bear against the latch plate, the latch plate cantingly locks against both the cylindrical tube and the connecting rod, thereby preventing the door from closing further. The door then remains held open in place until the blocking action of the latch plate is removed by virtue of the door being drawn slightly open, and the latch plate manually repositioned transversely along the connecting rod and away from the cylindrical tube, so that the connecting rod once again may slide through the latch plate aperture without the resistance formerely placed on the connecting rod.
One of the major disadvantages inherent in all such prior art devices concerns the oftentimes rather clumsy manipulation required when attempting to set or release the latch plate, either of which operation typically involves keeping the door held open with one arm while reaching towards and manipulating the relatively small and generally inaccessible latch plate with the other arm. It is not unusual that repeated attempts are required to set the latch plate at a discrete position along the connecting rod such that the door is held open to the desired amount. When there is insufficient light to illuminate fully the latch plate or when the latch plate must be manipulated by a user wearing gloves because of the weather, setting or releasing the latch plate may require repeated, time-consuming steps. Moreover, in situations not uncommonly encountered, where it may be desired to set the latch plate into locking position, the difficulties in manipulating, setting, and releasing the latch plate are exacerbated when one attempts to set the plate while transporting goods or while carrying an infant on one's shoulder. The user must attempt to support the goods or child in a non-conventional manner such as by carrying the weight on the user's hip or with a combination of torso and upper arm while holding the door open with the user's body and with the other arm to adjustably manipulate the hold-open latch plate transversely along the connecting rod until the plate is positioned in a locking orientation. Certain prior art devices have intended modifications to lessen or alleviate the difficulties associated with the standard latching mechanism. For example, U.S. Pat. No. 4,815,163 teaches a small extending lever to facilitate actuating the latching mechanism, U.S. Pat. No. 5,048,150 teaches a more complicated apparatus involving hydraulic pressure, and U.S. Pat. No. 4,722,116 teaches the use of wire cable lines to mechanically control the latch mechanism. These elaborate, multi-element structures are relatively more complicated and more time-consuming and more expensive to manufacture. Because of the complexity of the devices, one concern surrounding the use of them is whether they can operate repeatedly under all traffic and weather conditions.